Experiment 7: Polymers

The mechanical properties of polymers vary significantly from polymer to polymer as a result of atomic structure and bond strength. Thermoplastic polymers are generally composed of long coiling carbon chains that are primary bonded along the chains, but are secondarily bonded between chains. Thermoplastics tend to either contain crosslinks (primary bonds between chains) or are composed of three-dimensional space networks, but thermosets tend to be comparatively expensive and can’t be recycled. The tensile properties of representative samples from the three primary polymer types (thermoplastics, thermosets and elastomers) will be tested and evaluated. When a polymer is subjected to a constant strain yet realizes a decrease in stress as a function of time, it is said to be undergoing Stress Relaxation. Two experiments will be conducted on polymeric samples to investigate their stress relaxation behavior. The quantifying parameter, Relaxation Time Constant, will be determined for the two samples tested.

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